In recent years, various electronic apparatuses such as tablets, PDAs, and smart phones have been developed. In conventional electronic apparatuses, characters and commands have been input by inputting codes representing the characters and the commands, using keyboards, mouses, etc. In recent years, the electronic apparatuses have been provided with touch screen displays to facilitate the input. Characters, figures, commands, etc., can be input by handwriting them on screens or touching the screens.
A handwritten document is saved, not as image data, but as stroke data indicating coordinates on sampling points of each stroke constituting a character and the order of strokes (the order in which they were handwritten). At the time of retrieval, when a query stroke is handwritten, stroke data including a stroke having a similar feature to that of the query stroke is detected. However, in some cases, the character recognition of a handwritten document is performed, and a recognition result is saved with stroke data so that retrieval also can be conducted based on character codes (text data) as in a normal document processor. In general, character recognition is performed when a handwritten document is saved. Saving a handwritten document includes saving a new document, reading a handwritten document that has been once created and saved, and overwriting and saving it after edition. In the latter case of overwrite save, although the handwritten document after edition includes the same portion as the handwritten document before edition (already recognized portion), and character recognition of the whole document is performed.